Separation and recovery of soluble catalyst in hydrocarbon conversion reactions



M. H. GORIN ETAL 2,412,143

Filed April 23, 1945 3 Sheets-Sheet l HVVEIVTORJ' ATT'ORIVE'Y N9 A in HSEPARATION AND RECOVERY OF SOLUBLE CATALYST IN HYDROCARBON CONVERSIONREACTIONS :5 mm mm v T Q HH Ekuflk RQNQENN I 7 154M] Q um aw .QQYQSRW..QZQQ .ubb kk l2.

M. SEPARATION AND RECOVERY OF SOLUBLE CATALYST Dec. 3, 1946. H. GORINETAL m HYDROCARBON CONVERSION REACTIONS Filed April 23, 1945 3Sheets-Sheet 3 OVN . .H 1 wwmwmww meswmomv v tosvzoiuk H mww mmm k muhkn u ww ud p $8 I mmuvm hn w 0AN$N NM .flzvkbn MNN /M.$N 3N Q28 w kManuel L. Gorin fill Swerdlofi' INVENTORS AT TORNE'Y Patented Dec. 3,1946 SEPARATION AND RECOVERY OF SOLUBLE CATALYST 1N HYDROCARBON CONVER-SION REACTIONS Manuel H. Gorin and Will Swerdlofl, Dallas, Tex.,

asslgnors, by mesne assignments, to Socony- Vacuum Oil Company,Incorporated, New York, N. Y., a corporation of New York ApplicationApril 23, 1945, Serial No. 589,850

This invention relates to low temperature hydrocarbon conversionprocesses such as the alkylation, isomerization, reforming and the likeof light hydrocarbons.

More particularly this invention relates to such low temperaturehydrocarbon conversion processes which are carried out with the aid ofhy-' drocarbon soluble catalysts for the particular reaction involved.

The use of hydrocarbon soluble catalysts in solution in a hydrocarbon toeffect an alkylation reaction has been disclosed in copendingapplication Serial Number 416,864, filed October 28, 1941, now U. S.Patent 2,401,925, and to effect a reformingreaction has been disclosedin copend-. ing application Serial Number 412,108, filed September 24,1941, now U. S. Patent 2,383,123, both by Manuel H. Gorin. The use ofsuch catalysts to eflfect isomerization reactions is known. The processof this invention is applicable to any low temperature ydrocarbcnconversion reaction carried out wi h the aid of any hydrocarbon solubleisomerization, reforming or alkyla-tion catalyst. Aluminum bromide is aparticularly useful catalyst for these reactions, Examples of othersuitable catalysts of the type with which the process of this inventionis concerned are dialkyl aluminum chlorides, aluminum iodide, stannicchloride, dialkyl boron halides and the like.

The hydrocarbon soluble catalysts are of value in these low temperaturehydrocarbon conversion processes because of the ease with which intimatecontact between the catalyst and the reactants may be obtained. Becauseof the excellent con-tact obtained between the catalyst and thereactants, no special agitating or mixing equipment is required, as isnecessary where an immiscible liquid is the catalytic agent used.

Likewise in comparison with solid catalysts a much smaller amount ofcatalyst is required for molecular contact between catalyst and thereactants. Another advantage obtained by the use of soluble catalysts ascompared with solid or immiscible liquid catalysts is that theconcentration of the catalyst in the reaction mixture may be varied. Inmany of these hydrocarbon conversion reactions the same reactantsmaycombine in different ways to form several products. By varying thecatalyst'concentration, the reaction may be made to shift in favor of aparticular reaction to give a desired product as the major product ofthe interaction of the particular hydrocarbon reactant mixture.

The primary problem encountered in the u 7 Claims. (Cl. Mill-683.4)

of the soluble catalysts, which is not encountered in the broad sense inthe case of the use of insoluble catalysts, is that of separation of themain portion of the products from the major portion of the reactants andcatalyst. It is, therefore, a

primary object of this invention to provide for the ready separation ofproduct and catalyst, and

for the recirculation of the latter back to the for carrying out thereaction to the rate and conditions used for the separation of product,catalyst and unreacted hydrocarbons.

Other objects of the invention will be apparent from the descriptionthereof, and from the appended claims.

The general procedure followed in carrying out the hydrocarbonconversion process which forms the subject matter of our invention is tointroduce the hydrocarbon and other reactants, if required, into a,reaction zone, along with a hydrocarbon soluble catalyst; withdraw aportion of the reaction mixture containing products, unchangedreactants, and dissolved catalyst to a separation zone; divide themixture into two fractions in the separation zone, one consistingprincipally of a solution of catalyst in unchanged reactants and/orproduct, which is recirculated directly back to the reaction zone, andthe other, consisting essentially of product accompanied by varyingamounts of unchanged reactants, is drawn oif for subsequent recovery ofthe product. The product in this second fraction may be separated fromthe unchanged reactants, and minor amounts of catalyst carried alongtherewith, by any suitable method, and the particular method chosen willdepend to some extent on the characteristics of the product andreactants in the particular hydrocarbon conversion process to which ourmethod is applied. Generally a trimtional distillation of unchangedreactants from the product will be the most economical and the preferredmethod.

The method used to separate the bulk of the product from the-bulk of thecatalyst in the separation zone is that of evaporation. A conditionessential for the successful operation of the process is, therefore,that the boiling points of the product be sufficiently above that of thecatalyst at some pressure at which operation of the evap orator isfeasible so that the product may be vaporilefl While the catalyst willlargely remain as a liquid. But it is not strictly essential that theboiling points of the reactant or the various reactants be diflerentfrom the boiling points of either the product or catalyst. In thosecases where the product is lower boiling than the reactants, the processhas the additional advantage of sepaarting the product more or lesscompletely from the reactants, as well as from the catalyst.

- amazes line H, provided with pump IE to fractionator i1, wherein thetwo isomers are separated.

Where the reactants are lower boiling than the product, suificientreactant must be vaporized to.

carry over the product and separate it from the catalyst. In some caseswhere the product may be considerably higher boiling than the reactants,it is desirable to add to the reaction mixture a light volatilehydrocarbon or other inert volatile liquid or gas, which will not reactwith added light hydrocarbon or the passage of the 1 inert gas throughthe separation zone will assist in the carrying over of the product.

Suflicient hydrocarbons must be associated with the catalyst leaving theseparation zone to keep the catalyst in solution, and thus avoid anyundesirable precipitation of the catalyst. This im-. poses a limit uponthe amount of hydrocarbons which may be vaporized in the separationzone. Where the product is more volatile than the unreactedhydrocarbons, these unreacted hydrocarbons furnish the necessarycatalyst solvent. In the case where the reactant is more volatile thanthe product, a considerable quantity of product along with some reactantmay be recycled with v the catalyst and returned to the reaction zone.

- Our invention may be best understood from the following descriptionthereof in conjunction with the discussion of the drawings:

In the drawings:

' Figure 1 shows diagrammatically an apparatus for carrying out theinvention when applied to an isomerization reaction in which the productisomer is lower boiling than the reactant isomer.

Figure 2 shows diagrammatically an apparatus for carrying out theinvention when applied to an alkylation reaction.

. Figure 3 shows diagrammatically an apparatus for carrying out theinvention when applied to a reforming reaction of the type in which anatural gasoline is reformed to yielda product having a higher octanrating.

Referring to Figure 1,'a hydrocarbon charging stock, such as normalbutane, is fed into reactor K, through line 2, in which is located pump3 and valve a. Make up aluminum bromide, or other soluble catalyst,preferably in solution in n'ormal butane is fed into the reactor throughline 5, provided with pump 6 and valve I. In reactor i, the'charge stockis maintained at a temperature favorable to the isomerization reactionwhich progresses therein, and at a'pressure sumcient to maintain thenormal butane in the liquid phase. The reaction mixture flows outthrough line 8 to heat exchanger 9, wherein the necessary heat ofvaporization is supplied to it. From the heat exchanger the mixtureflows through line H) to evaporator I I in which'the vapors areseparated from the liquid. In evaporator H the more volatile isobutaneand a portion of'the normal butane are converted to vapor and pass outthrough line [2 to condenser I3, from which the condensate collects inreceiver H. The condensate then passes from the receiver throughheptanes.

ilcient amount of hydrocarbons to keep it in sol The higher boilingcatalyst and much of the norma1 butane together with some isobutaneremain in the liquid state, and flow from the bottom of the evaporator,through line I8 to a cooler I9, wherein they are brought back to thetemperature in the reactor, and returned to the reactor. through line20, which is provided with a suitable pump 2!.

The temperature of the reaction mixture going to the evaporator, and theconditions therein are adjusted so as to evaporate the isobutane ascompletely as possible without throwing out of solution or evaporatingany appreciable amount of catalyst. The distribution oi'the normalparaffin between overhead and bottoms will, of course,

depend upon the evaporator design, conditions of operation, and upon thedegree of proximity of the boiling points of the reactant isomer and theproduct isomer. i

In fractionator H the product, isobutane, is

separated from normal butane and passes overhead through line 22 tocondenser 23 and then through line 24 to storage tank 25'. Suitablemeans (not shown) are provided to furnish nec' essary reflux forfractionation. The normal butane, in the bottoms from the fractionator,passes through line 26, provided with pump 21 to line 2, where it mixeswith the normal butane feedinto the reactor..

Reactor i is provided with a conical bottom 28 in which spent catalyst,in the form of a com, plex between the eatalystand hydrocarbons,collects. This spent catalyst is either drawn off continuously or drawnoff from time to time as it accumulates, through line 29, controlled byvalve 30 for purification and recovery.

Figure 2 shows the principles of our invention applied to an allrylationreaction. An isoparaf- .fin, such as isobutane, is fed to reactor Hll,

through line Hi2, provided with pump I03 and valve HM. Make up aluminumbromide, preferably in solution in isobutane, is introduced into thereactor through line )5 in the same manneras described in the discussionof Figure 1. An

alkylating agent such as propylene is introduced into reactor Elli,through line 835, provided with pum i132 and valve 33. 'The reactionmixture after being heated as described in theydiscussion of Figure 1-,is fed into the evaporating concentrator ill, whichv is provided withheating coil (134 to furnish part of the necessary heat of va-Iporization. In the case of-an alkylation reaction,

the product, in this case branched chainheptahes,

sider'able excess of the isoparaihn reactant to minimize side reactionsof the olefin. The vaporization of this isobutane helps carry over theThe higher boiling catalyst and a suflution flow from evaporator HI backto reactor IOI, after being cooled to reaction temperature in cooler i Hin the manner described above.

The-vapors from evaporator Ill are condensed and. sent to fractionatorill, wherein the tanes and isobutane are separated. The conden sationmay be 'efiected by cooling as shown'i Figure 1; or alternatively, tofurnish much of th' soluble catalyst necessary heat of vaporization,compressed by compressor through heating coil I34, wherein at least a,portion of the vapors condense and thus heat of condensation furnishesmuch of the necessary heat of vaporization. The overhead is then passedvia line I38 through condenser I I3 to condense any uncondensed vaporsand the total'condensate passed to receiver 4. In the case of thealkylation reaction, the product is the higher boiling and is drawn oilfrom the bottom of the fractionator for storage in tank I25. Theisobutane vapor passes overhead and is condensed in condenser I23 andreturned to reactor IOI, through line tane feed line I02. age tank I25,through line I35, pump I36.

Figure 3 ShOWs the principles of our invention applied to a typicalreforming process in which a natural gasoline is reformed in thepresence of a such as aluminum bromide to give a product having a higheroctane rating. The natural gasoline, containing 5 to 9 carbon atomhydrocarbons is fed into the reactor 20I, through line 202, and aluminumbromide is introduced in the manner previously described. The reactoreilluent is transferred via line 20!! to evaporator 2| I. Evaporator 2IIi operated under conditions so that the gasoline, and lower boilinghydrocarbons are vaporized and carried over after condensation tofractionator 2". To secure the desired vaporization it is usuallydesirable' to introduce some C4 hydrocarbons into the reaction mixtureprior to their passage into the evaporator. The necessary C4hydrocarbons are introduced through line 224 to line 208, carryingthereaction mixture. During the reforming operation some C4 hydrocarbonsare produced, as well as some higher boiling hydrocarbons of from 10 to12 carbon atoms. Additional C4 hydrocarbons, however, make it possibleto vaporize the desired fraction without excessive heating of thereaction mixture, thus minimizing catalyst vaporization and undesirableside reactions.

The material not vaporized in evaporator 2 mainly hydrocarbons of 10 to12 carbon atoms and the catalyst is recycled via line 2I8, cooler 2I9,and line 220 to reactor I. In the reactor these long chain hydrocarbonsreform to shorter chain carbon atom hydrocarbons.

The vapor from the evaporator passes to fractionator 2I'I wherein the C4hydrocarbons are separated from the gasoline boiling hydrocarbons, whichare removed as bottoms and sent to storage tank 2251 The butane vaporsare passed overhead via lin 222, condensed in condenser 223, andreturned to the process to carry over more gasoline boiling productthrough line 224. As mentioned above, some butanes are formed in Theproduct passes to storprovided with the process, and to prevent acontinuous accumulation of butanes in the system, the excess butanesformed are removedthrough line 240, and accumulated in storage tank I.Valves 242 and 243 are provided in lines 224 and 240, respectively, tocontrol the division of flow of the butane.

The following examples illustrate the manner of carrying out ourinvention:

Example I A mixture of 3.41 gallons of feed containing 3.10 gallons ofn-butane plus 0.031 gallon of aluminum bromide is added per hour to areactor I24, where it joins with the isobu-'- the vapors are 7 I58 andpassed 6 maintained at a temperature of 168 F. and at a pressure 015atmospheres absolute. The rate of discharge-of the mixture from thereactor was 3.44 gallons per hour. The composition of the reactordischarge was 2.1? gallons of n-butane,

1.21 gallons .of isobutane, 0.029 gallon of aluminum bromide, and thebalance was principally isopentane. This mixture was then passed to aconcentrating evaporator operated at a temperature of F. and at apressure of 41 pounds per square inch absolute. The amount of condensedvapor removed overhead per hour from the evaporator was 2.'75 gallons.The composition of this overhead was 1.74 gallons of n-butane, 1.00gallon of isobutane, and 0.01 gallon of isopentane.

The bottoms from the evaporator consisted of catalyst concentrate andamounted to 0.69 gallon per hour, of which 0.028 gallon was aluminumbromide, 0.44 gallon was n-butane, 0.21 gallon was isobutane and 0.01gallon was isopentane. This catalyst concentrate was returned to thereactor.

The condensed overhead was passed to a fractionator feed ,tankoperatedat a pressure of 69 pounds per square inch absolute, and at atemperature of F. from which it was fed to the fractionator forseparating the isobutane product, 0.98 gallon per hour from then-butane. The n-butane was returned to the reactor.

The total material returned to the reactor was 0.028 gallon perhour ofcatalyst returned in the catalyst concentrate, 2.18 gallons per hour ofn-butane, of which 0.44 gallon was returned with the catalystconcentrate, 0.21 gallon per hour of isobutane in the catalystconcentrate, and 0.02 gallon per hour of isopentane. With steady stateconditions in order to maintain a total feed return to the reactor of3.41 gallons per hour, 0.97 gallon of fresh feed was added per hour, ofwhich 0.93 gallon or 96% was n-butane. Make up catalyst in an amount of0.003 gallon per hour was required.

Example I] To a reactor operated at a' temperature of 110 F. and at apressure of 200 pounds per square 'inch absolute was fed 0.87 gallon ofethylene per hour and 1.22 gallons per hour of raw isobutane.

charge from the reactor was 6.13 gallons per hour,

of which 4.07 gallons represented unreacted isobutane, 1.04 gallonsrepresented the hexane products and the balance hydrocarbons of from 3to 10 carbon atoms, predominantly n-butane, octanes and decanes.

The reaction mixture was fed to an evaporator maintained at a pressureof 8.1 pounds per square inch absolute and at a temperature of F. Theoverhead from the evaporator represented 5.7? gallons per hour, of which4.04 gallons were isobutane and 1.00 gallon was hexane. The bottoms fromthe evaporator were 0.36 gallon per hour of hydrocarbons containingsubstantially all of the catalyst, and were recycled directly to thereactor. The overhead from the evaporator was sent to a fractionator(deisobutanizer) feed tank operated at a pressure of 61 pounds persquare inch absolute and at a temperature of 100 F. from which it wasfed to the fractionator. The-bottoms from this fractionator containedthe hexane product in an amount of 1.00 gallon mixed with 0.55 gallon ofother hydrocarbons, principally octanes and decanes. The overheadamounted antenna to 4.22 gallons per hour, of which 4.02 gallons wereisobutane, and the balance principally, nbutane, which was recycled tothe reactor. The total feed to the reactor, including recycled material,was 6.6? gallons per hour. The volume of reactor used was 40gallons,'giving an average reaction time of 6 hours. For every gallon oihexane product a fresh feed of 0.87 gallon of ethylene and 1.20 gallonsof isobutane were required. The ethylene was completely reacted.

, The ratio of isobutane to ethylene in the reactor was 5.24 gallons to0.8? gallon, or substantially a molar ratio of 4 to 1. The amount ofcatalyst 10st, principally in the form of an insoluble complex withhydrocarbons settling out from the rewith other olefins such spentenabutylene, and I propylene, and to the alkylation of isoparailinswith other alkylating agents such as the various actor amounted to 0.005gallon per hour, which are not to be construed as limiting theinvention.

As stated in the objects of the invention .it is applicable to any lowtemperature hydrocarbon conversion reaction which may be catalyzed by ahydrocarbon soluble catalyst. The invention is not intended to includewithin its scope high temperature hydrocarbon conversion reactions suchas cracking. The reactions with which this invention is concerned aregenerally carried on at temperatures below 150 to 200 C., althoughsomewhat higher temperatures may be used in special cases. In generalthe reactions are characterized in that they do not involve theformation of appreciable amounts of fixed hydrocarbon gases such ashydrogen, methane and ethane by decomposition and cracking oi? thehydrocarbons undergoing reaction.

. Since the reactionwlth which the invention is concerned involvestheuse of a hydrocarbon soluble catalyst, a condition of the reaction isthat a hydrocarbon be present in the liquid phase. It

is. essential, therefore, that the reaction temperature be below thecritical temperature of the hydrocarbon or hydrocarbon mixture whichserves as a solvent for the catalyst. This liquid hydrocarbon isgenerally one of the reactants in the process, although in special caseswhere an inert hydrocarbon is added to serve as a carrier for theproduct in the separation zone, the hydrocarbon'reactant or reactantsmay b introduced as gases for convenience and to produce agitation ofthe reaction mixture in the reaction zone.

The invention has been illustrated as applying to isomerlzation,reforming, and condensation reactions in general. Obviously, in additionto the isomerization of normal butane to isobutane the invention isequally applicable to the isomerization of other normal paraifins suchas n-pentane,

n-hexane and the like to the corresponding isoparaflins, and to theisomerization of the isoparafflns to the normal paramns should this bedesired. The invention is equally applicable to other isomerizationreactions such as the isomerization of methyl cyclopentane tocyclohexane, and to isomerization of aromatic hydrocarbons. Typicalcondensation reactions which have been used to illustrate the inventionare the a1- kylation reactions, such as the formation of 2,3-

dimethyl butane by the alkylation of isobutane with ethylene. Obviously,the invention is applicable to the alkylation of other isoparafins bepartiallyvaporiZ-ed in the heater and the two- 'alkyl halides, etc.particularly useful in the alkylation of isobutane and ethylene, whichreaction is very advanta-,

The invention ,has proven geously carried out in the presence of analuminum bromide catalyst.

No particular type of concentrating evaporator is required forseparation of the product and the catalyst. Where the product is readilyvolatilized a simple flash evaporator may be used. Where a flashevaporator is used it should be provided with suitable baifle plates tominimize entrainment of higher boiling hydrocarbons and cat-- alyst inthe outgoing vapors. Generally, the reaction mixture being fed to'theevaporator will phases will complete their separation in the evaporatoritself. Any suitable heating coil may be inserted in the evaporator. Itis generally desirable to operate the evaporator at relatively lowpressure in order to reduce the temperature required to vaporize thedesired component of the reaction mixture. Where a normally inert gas isused as the stripping agent, such as methane, the

gas may be heated prior to introduction into the evaporator wherein itserves as the stripping agent. The essential requirements are theoperation of the evaporator under such conditions of temperature,pressure, and heat input that sufllcient hydrocarbons are retained inthe liquid phase to keep the soluble catalyst substantially completelyin solution, and the substantially complete removal of the vapor phasefrom the even-- oration zone before condensation to avoid the return ofany substantial amount of the overhead to the liquid phase in theevaporator for further contact with the catalyst or to the reaction zonewith the catalyst recycle. Refluxing of liquefied overhead should beavoided insofar as practicable since it will promote possible sidereactions of the products as well as permit any high boiling materials,.as, for example, heavy alkylate formed in an alkylation reaction orpentanes formed in a butane isomerization procass, to accumulate in thereaction zone.

The concentration of the catalyst in the reaction zone should be wellbelow the saturation value in the reaction mixture under the conditionsof temperature to be employed in the evaporator since his desirable toeffect a considerable concentration of the reaction eiiiuent in theevaporator recycle, and, therefore, the amount of. solvent to berecycled may not be sumcient to retain the catalyst in solution were ahigh concentration in the reactor employed. This is particularly true inthe case of an alkylation reaction where the product is higher boilingthan the reactants requiring that a substantial proportionof thehydrocarbons to vaporized to carry over appreciable product. Higherconcentrations are usually permissible in isomerization reactions, suchas n-butane isomerization, since the product isomer is usually lowerboiling than the reactant hydrocarbon, but even in these isomerizationreactions, the concentrations of catalyst in the reaction zone shouldnot exceed about 50 to 60% of the saturation value under thevaporization conditions. Itis to be realized of course, that there willbe some difierence in the solubility in the reactor efiiuent from thatin the non-vaporized solvent from the evaporator because of difi'erencesin composition or these hy-' drocarbon mixtures. These diflerences inthe usual case are not generally large, and favor retention of thecatalyst'in solution since the solubility generally increases in thehigher hydrocarbons.

Since these reactions are generally exothermic, suitable cooling meansmaybe found necessary for the reaction zone to maintain the reactiontemperature at the desired level. These cooling means may be theconventional cooling coils placed in or around the reactor. One methodwhich has been found particularly useful in controlling the temperatureof the reactor is to operate at a pressure so that a portion of thereaction mixture is vaporized as a result of the exothermic heat of thereaction. These vapors are withdrawn from the reaction zone andcompressed. A portion of the compressed gases may be condensed and thiscondensate recirculated to the reaction zone wherein its subsequentvaporization will control the temperature by taking up excess heat ofreaction. Another portion of this compressed gas may be recirculated tothe bottom of the reaction zone and introduced through a suitable bubbleplate. This gas in rising through the reaction zonewill produce sum--cient agitation for a reaction of this type involving the use of asolublecatalyst. 7

Since some agitation is desirable even though a soluble catalyst isused, it is frequently desirable to introduce one oi, the reactants,where two are involved, or a portion of the reactant, where only onereactant is involved into the bottom of the reactor in the gaseous phaseto furnish the desired agitation. In those cases in which it isdesirable to have a hydrocarbon carrier present to assist in thevaporization of the product from the catalyst in the separation zone,the catalyst may be dissolved in the hydrocarbon carrier and all of thereactant material introduced as a gas.

In the description oi. the invention and in the drawings, a heater hasbeen interposed between the reaction zone and the separation zone osupply heat for vaporization of the product. In cases where it isundesirable to have the evaporation temperature much or any higher thanthe reaction temperature the vaporator may be operated at a much'reducedpressure to secure the necessary vaporization. Naturally some heat mustbe supplied in any case to supply the heat of vaporization for theproduct vapors and for any reactant and carrier vapors formed in theseparation zone. A heating coil, placed in the evaporator, will serve tosupply the necessary heat as the vaporization occurs.

Since it is generally desirable to feed the product-containing vaporinto the fractionator as a liquid, this vapor may be compressed as itleaves the evaporator and recirculated in heat exchange relationshipwith the evaporator or the evaporator feed, for at least partialcondensation of these compressedvapors. The heat condensation of thiscompressed product-containing vapor will supply part of the heatnecessary to evaporate the desired components of the evaporator feed.This has been shown diagrammatically in Figure 2. This return of theheat of evaporation to the evaporator would not be 100 percent completeand some additional heat would be required for the evaporator feed. Thisamount might be kept to a fairly low value, making it feasible to supplythis additional heat to the evaporator feed at a relatively lowtemperature level, thus minimizing the temperature rise of theevaporator feed.

As mentioned previously in the discussion of.

Figure 1, a portion of the catalyst must be continuously drawn oil forregeneration because oi! the continuous formation of a complex betweenthe soluble catalyst and the hydrocarbons. Even though this catalysthydrocarbon complex may have considerable catalytic activity, it isimmiscible with the hydrocarbon and tends to accumulate in the bottom ofthe reaction zone. This catalyst should be drawn off and regenerated torecover the active catalytic compound. The particular method used forregeneration of the catalyst will depend upon the soluble catalyst used.This recovered catalyst will then be returned to the reaction zone. Thecatalyst recovery will not be 100 percent complete and a small amount ofcatalyst may likewise be carried over with the reaction products. berequired, as is customary in the case of catalytic reactions, and thismake up catalyst may be added along with the regenerated catalyst.

In the foregoing description. of our invention, the process has beenillustrated as applied to a fully continuous process, in which thecatalyst containing hydrocarbon mixture is continuously withdrawn from areactor, circulated to an evaporator from whence the unvaporized,catalystcontaining, portion is continuously returned to the samereactor. Frequently it may be preferable to use a battery of reactorswith a single evaporator. In such operation the evaporator would operatecontinuously, but the operation of each unit in the battery of reactorswould be. strictly speaking, discontinuous. That is one reactor would bedischarging at all times to the evaporator. The unvaporized hydrocarboncatalyst' mixture would be returning to another reactor, which alsowould be receiving fresh feed for reaction. The remaining reactors inthe battery would-be temporarily operating as batch reactors. When thecontents of the discharging reactor had been removed to a predeterminedextent, another reactor would be set to discharge to the evaporator, andthe unvaporized material from the reactor set to return to a dischargedreactor. Suitable valves would be provided to provide the desiredsequence of operation for charging and discharging of each unit in thebattery of reactors. The sequence of operation of such a battery ofreactors might be a series operation. In such a case the discharge tothe evaporator would be,

constant from the last reactor in the series, and the unvaporizedcatalyst containing mixture returned to the first reactor. Theintermediate reactors would contain reaction mixture in which thereaction had proceeded in varying degrees towards completion. Any otherdesired sequence" of operation might be followed in some of which eachreactor unit would be operated for a portion of the time as a batchunit, completely disconnected from the evaporator, and only periodicallywould discharge to the evaporator and recycling of the feed occur.

This application is a continuation-in-part of our prior application S.N. 448,886, filed June 29, 1942. I

Many other modifications of our invention will be apparent to thoseskilled in the art and. therefore only such limitations should beimposed as are indicated in the appended claims.

We claim:

1.- The method of conducting a low temperature hydrocarbon conversionreaction in which at least one reactant is a hydrocarbon which comprisesconducting the reaction in a reaction zone S'ome make up catalyst will Icatalyst to the reaction zone.

having dissolved therein a hydrocarbon soluble before any substantialcondensation thereof, regulating the amount of vaporization so thatsumcient hydrocarbon remains in the liquid state to act as a solvent forthe hydrocarbon'soluble catalyst, condensing the product vapors removedfrom said separation zone so that return of condensed product vapors tothe catalyst solution is substan! tially. avoided, recovering productfrom the condensate, and recycling the unvaporized portion or thereaction mixture containing the dissolved 2. The process of claim 1 inwhich the catalyst is aluminum bromide.

3. A processior'the alkylation of hydrocarbons by the reaction of anisoparaflln with an alkylating agent in which the isoparaflin is reactedin the liquid phase in a reaction zone and in which a hydrocarbonsoluble catalyst characterized by having a boiling point above that ofthe desired alkylate product is dissolved in the isoparaflin whichcomprises alkylating an excess of the isoparafiin with the alkylatingagent in the reaction zone, withdrawing liquid reaction mixture con-'taining alkylate product, excess isoparafiin reactant and dissolvedcatalyst from said reaction.

zone, transferring the withdrawn mixture to a separation zone,vaporizing alkylate product from the reaction mixture in said separationzone, removing the alkylate' vapor from said separation zone before anysubstantial condensation thereof, regulating the amount of vaporizationso that sufficient hydrocarbon remains in the liquid'state to act asasolvent for the hydrocarbon soluble catalyst, condensing the alkylateproduct vapors removed from said separation zone so that return ofcondensed alkylate to the catalyst solution is substantiallyavoided,recovering alkylate product from the condensate, and recyclingthe unvaporized portion of the hydrocarbon mixture containing thedissolved catalyst to the reaction zone. a

4. The process of claim 3 in which the catalyst is aluminum bromide.

5. A process for the alkylation of hydrocarbons by the reaction of anisopa'raflin with an olefin in which the isoparafiln is reacted in theliquid phase in a reaction zone and in which a hydrocarbon solublecatalyst characterized by having,

a boiling point above that of the desired alkylate product is dissolvedin the isoparaflln which comprises alkylating an excess of theisoparaflln having the hydrocarbon soluble catalyst dissolved thereinwith the olefin in the reaction zone, withdrawing liquid reactionmixture containing alkylate product, excess isoparafinic reactant anddissolved catalyst from said reaction zone, transferring the withdrawnmixture to a separation zone, vaporizing product from the reaction mix--ture in said separation zone, removing the alkylate product vapors fromsaid separation zone before any substantial condensation thereof,regulating the amount of vaporization so that sumcient hydrocarbonremains in the liquid state to act as a solvent for the hydrocarbonsoluble catalyst, condensing the product'vapors removed from saidseparation zone together with isoparaflinic reactant vaporized therewithso that return of condensed vapors to the catalyst solution issubstantially avoided, transferring the condensed isoparaflin-alkylatemixture to a fractionationzone and therein separating the excessisopar-' afiinic reactant and product, recycling the isoparaflin to thereaction zone, recycling the unvaporized portion or the reaction mixturecontaining the dissolved catalyst to the reaction zone, and recoveringthe alkylate product.

6. A process for the isomeriz'ation of hydrocarbons which comprisesconducting the reaction in a reaction zone with the hydrocarbon to beisomerized in the liquid phase and having dissolved therein ahydrocarbon soluble catalyst characterized by having aboiiin pointabovethat of the desired product isomer as the effective catalyticagent, withdrawing liquid reaction mixture containing product isomer,the hydrocarbon and dissolved catalyst from said reaction zone,transferring the withdrawn mixture to a separation zone, vaporizingproduct isomer from the reaction mixture in said separation zone, re-

moving the product vapors from said separation zone before anysubstantial condensation thereof, regulating the amount of vaporizationso that sumcient hydrocarbon remains in the liquid state .to act as asolvent for the hydrocarbon soluble catalyst, condensing the productisomer vapors removed from said separation zone together with any vaporsof the hydrocarbon to be isomerized 1 so that return of the condensedvapors to the catalyst solution is substantially avoided, transferringthe condensed vapor mixture to fractionation zone and therein separatingthe hydrocarbon isomer from the hydrocarbon to be isomerized, recyclingthe unreacted hydrocarbon to be isomerized to the reaction zone,recycling theunvaporlzed portion of the reaction mixturev containing thedissolved catalyst to the reaction zone,-

and recovering the product isomer.

'7.- The process of claim 6 in which the catalyst is aluminum bromide.

o MANUAL H. GORIN.

WILL SWERDLOFF.

